Improved Reversible Pump-Turbine Installation

ABSTRACT

The present invention is a reversible pump-turbine installation position in a vertical shaft instead of in a conventional underground powerhouse or deep concrete powerhouse. The required plant cavitation coefficient may be achieved by simply boring a vertical shaft to the required depth rather than routing the water flow to and from a deeply buried powerhouse. A pneumatically controlled pressure relief valve may be incorporated into this invention.

FIELD OF THE INVENTION

The present invention relates to reversible pump-turbines used forstorage of electrical energy. Conventional pumped storage facilities asshown in FIG. 1b generally use an underground powerhouse to providesufficient absolute pressure at the runner to prevent destructivecavitation. The elevation of the runner may be 100 meters belowtailwater, for example. Constructing and maintaining such an undergroundfacility is expensive and the expense does not decrease in proportion tosize in the case of smaller facilities. There are therefore very fewpumped storage facilities of less than 100 MW in North America. Atypical conventional pump-turbine sectional elevation is shown in FIG.1b . The prior art pump-turbine flow path with a 90 degree turn in themeridional plane is illustrated in FIG. 1c , this being similar to theflow path in the meridional plane of a conventional Francis turbine. Thepresent invention relates to single purpose turbines and pumps as wellas to reversible pump-turbines. With respect to prior art multi-stagepumps, the relationship between the impeller and diffuser in themeridional plane is shown in FIG. 2, where the acceleration imparted bythe runner (impeller) to the fluid is outward and downward, this resultsin an unnecessarily small runner tip diameter compared to the maximumwater passageway diameter that in this case occurs in the diffuser. Thisunnecessarily small diameter results in limited head differential acrosseach stage and in turn results in more stages and lower overallefficiency.

SUMMARY OF THE INVENTION

The present invention establishes the required plant cavitationcoefficient by positioning reversible pump-turbines withmotor-generators, generally well below tailwater level in a generallyvertical bore hole. Reversible pump-turbines with motor-generators willbe referred to herein simply as “pump-turbines” or as “machines” Theterm “bore hole”, rather than “shaft”, is used herein to avoid confusionwith the rotating shaft of the pump-turbine located therein.

Conventional pumped storage facilities position the runner well belowtailwater elevation to suppress cavitation while keeping unit power andspecific speed high. The critical cavitation coefficient for reversiblepump-turbines is higher than it is for either turbines or pumps becausethe hydraulic profiles are a compromise between pumping and generatingand are optimized for neither. Positioning of the runner below tailwaterhas heretofore required a deep and expensive excavation regardless ofmachine size and rating. The expense of excavation and undergroundconstruction has been cost prohibitive for small installations, of lessthan 100 MW, for example. Sites suitable for large installations arelimited by geology, geography, competing land uses, and adequatetransmission lines. Many suitable smaller scale sites exist, butexisting reversible pump-turbines, even if scaled down in size andrating, still require excavation and construction costs that areprohibitive.

The proposed configuration utilizes a simple and inexpensive bore holeof perhaps 1 to 3 meters in diameter to position a high specific outputreversible pump-turbine sufficiently below tailwater elevation tosuppress cavitation. Such bore holes are routinely drilled as acommodity construction service for reasonable prices. A steel liner andconduits for hoisting water, electrical and control cables, for example,may be grouted in place within the bore hole. Pump-turbines adapted tothis type of installation may be configured as single stage machines ormay be configured as multi-stage machines utilizing specially configured“diffuser bowls” similar in function to those used on multi-stagesubmersible pumps. These pump-turbines would not normally useconventional scroll cases. As such, stages of these pump-turbines may bestackable to allow standard hydraulic designs to be used over a widerange of head conditions. The use of standard pump-turbine stages isfurther facilitated by the fact that the required plant cavitationcoefficient can be achieved by simply establishing the required verticalbore hole depth. Compared to conventional underground powerhousepump-turbine installations, there is a less frequent need to design andmanufacture site specific machinery and there is no need carry thepenstock nor tailrace conduit to extraordinary depths, which would becost prohibitive in conjunction with small pumped hydro installations atmost locations. The use of standard components results in increasedquantities of like parts at reduced cost. Reduced costs in turn enable agreater number of projects to be built with increased part quantities.

Water flow to and from the reversible pump-turbine may be throughcoaxial penstocks positioned in the shaft above the pump-turbineassembly. The associated motor-generator may be submersible and incertain preferred embodiments located below the pump-turbine(s).Locating the motor-generator below the pump turbines allows for a largerdiameter, and therefore more economical, motor-generator for a givenbore hole size. Allocating substantially all of the bore hole crosssectional area to water conveyance (up and down), rather than to spacefor the motor-generator, allows for the maximum power rating for a givendiameter of bore hole.

The generator may alternatively be located outside of the waterpassageways and connected to the runner with a shaft. Such anarrangement may be cheaper than providing an underground powerhouselarge enough to incorporate a scroll case, while allowing the use of areadily available air-cooled generator.

In a preferred embodiment, a removable manifold may be used to connectthe inner pipe to tailwater and connect the outer pipe to the penstockleading to headwater. It is generally more efficient to connect thesmaller diameter pump inlet/turbine outlet with the smaller of thecoaxial pipes while connecting the larger pump outlet/turbine inlet withthe larger of the two coaxial pipes. Alternative embodiments of thisinvention may utilize another arrangement as may be the case whenmultiple pump turbines might be installed, on a bulkhead, for example,in a common bore hole. The removable manifold may include an integralpneumatically controlled pressure relief valve. This integral pressurerelief valve will itself reduce civil works costs by eliminating theneed for a surge shaft and by reducing penstock surge pressure andpenstock cost. Additionally, or alternatively, an air cushion may beleft under the cover of the bore hole. Removal of the manifold allowsremoval of the machinery from the borehole. Dedicated hoisting equipmentwill facilitate installation, service, and maintenance without the needfor confined space work. A water pressure actuated piston attached tothe bottom of the eversible pump turbine may be used for raising andlowering. A spacer between the piston and the machine may be used toallow the machine to be raised entirely clear of the borehole.

Variable speed operation is facilitated by the ready availability ofpower control electronics developed for the wind industry. As in thecase of wind turbine power converters, full power converters may be usedin conjunction with permanent magnet motor generators and partial powerconverters may be used in conjunction with (generally larger) doubly fedinduction generators.

The bore hole in which the reversible pump-turbine is installed mayinclude provision for delivery of pressurized water to the bottom of theshaft, through a conduit separate from the main bore hole tohydraulically hoist the equipment for maintenance and repair and tocontrollably lower the equipment into operating position. The electricalpower connection is preferably configured to automatically engage whenthe machine is lowered and to automatically disengage when the machineis raised. Such a connector may use conventional “wet mate” marineelectrical connector technology or may be use a combination ofcompressed gas, insulating oil and inflatable seals, for example, toestablish robust electrical connections isolated from ground potential.

The bore hole in which the equipment is located may terminate at theupper portal, the lower portal or at any convenient intermediatelocation. In the case of installation in conjunction with an existingpipeline, the vertical shaft may be located according to desiredpressure profiles resulting from operation, load rejection, and otherconsiderations. The shaft cover may incorporate a pressure relief valveand may be used to cap off a surge shaft containing air.

Multiple machines may be installed in a single shaft, on a commonbulkhead, for example. The reversible pump turbines in accordance withthe present invention may be used in conjunction with Pelton turbines,for example to facilitate generation at low power levels if required.The reversible pump turbines may be used in conjunction with off-streamseasonal storage reservoirs, where their primary purpose may be to raisewater to the storage reservoir during high flow periods and to returnwater while recovering energy when stored water is required downstream.

In accordance with certain embodiments of this invention, gas pressurebalanced pressure relief valves may be used to limit overpressure fromwater hammer.

An elbow with actuatable seals may be used in order to connect the drafttube to the tail race during operation. Inflatable seals may be used toseal the elbow in its operating position while allowing it to movefreely during hoisting and lowering operations. Inflatable seals orsupports may also be used to fix the machine into position duringoperation and to release it to allow it to be raised for maintenance.

In accordance with a further aspect of the invention a reversible pumpturbine runner or pump impeller is provided that imparts to the flow anupward velocity component. This upward velocity component allows theflow to proceed directly up through the diffuser or a guidevane-diffuser combination in the case of a reversible pump-turbine, ordirectly to a diffuser (stator) stage in the case of a multi-stage pump,while maximizing the ratio of impeller tip diameter to maximum waterpassageway diameter. In the case of the present invention this ratio maybe 1.00. This maximizes the head per stage and allows a greater head tobe achieved with a single stage machine. FIGS. 19 a, 19 b, and 19 cillustrate the flow in the meridional plane as well as the X-shapedappearance of the impeller blades when viewed toward the trailing edge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a conventional (prior art) pumped storagefacility.

FIGS. 1b and 1c are sectional elevation drawings of a conventionalpump-turbine.

FIG. 2 is a schematic of a pumped storage facility in accordance withthe present invention.

FIG. 3 is a section through the meridional plane of a multistage pump ofprior art.

FIG. 3a is an elevation view of the pumped storage facility of FIG. 3ashown with the pump-turbine assembly partially removed.

FIGS. 4a and 4b are sectional elevations of a pressure relief valveconfigured for use with the present invention.

FIG. 5a-c are sectional elevation drawings of a reversible pump-turbinein accordance with the present invention.

FIG. 6 is a cutaway rendering of a reversible pump-turbine andassociated pumped storage facility in accordance with the presentinvention.

FIG. 7 is a cutaway view of an elbow connection to the tailrace tunnelwith an inflatable seal to secure and seal it in accordance with thepresent invention.

FIG. 8 is a sectional elevation drawing of a pump-turbine installationwith the vertical borehole collocated with the headworks in accordancewith the present invention.

FIG. 9 is a sectional elevation drawing of a pump-turbine installationwith the vertical borehole collocated with the tailrace portal inaccordance with the present invention.

FIG. 10 is a sectional elevation drawing of a pump-turbine installationwith the vertical borehole located between the headworks and thetailrace portal in accordance with the present invention.

FIG. 11 is a sectional elevation drawing of a pump-turbine installationwith the vertical borehole located in association with an undergroundpressured water storage cavity that serves as the “upper” reservoir.

FIG. 12 is a schematic of a pump in accordance with the presentinvention in association with an air/water accumulator, most likelyunderground, and a gas turbine.

FIG. 13 is a schematic of a pump in accordance with the presentinvention in association with an air/water accumulator, most likelyunderground, and a gas turbine, wherein the air may be nearlyisothermally compressed with the aid of water spray cooling.

FIG. 14 illustrates a tailrace connection elbow in accordance with thepresent invention that incorporates an inflatable seal that also servesas an adjustable pressure relief element. The inflatable seal (63)features a flow separation control fin 51 to reduce vibration duringoperation.

FIG. 15 illustrates a pumped storage installation in accordance with thepresent invention including a a tailrace connection elbow.

FIG. 16 illustrates a pumped storage installation in accordance with thepresent invention including a tailrace connection elbow and a penstockentering the borehole at an elevation higher than the tailrace tunnel.

FIG. 17 illustrates a pumped storage installation in accordance with thepresent invention including a tailrace connection elbow.

FIG. 18 illustrates a pumped storage installation in accordance with thepresent invention including a tailrace connection elbow.

FIGS. 19a and 19b are meridional plane sections of a multistage pumpimpeller in accordance with the present invention.

FIG. 19c is and end on view looking into the discharge edge of theimpeller of FIG. 19 b.

FIG. 20 is a plan view schematic of 3 pump turbines installed inassociation with a single penstock and a single tailrace tunnel.

FIG. 22a is a pump turbine installation including a pressure reliefvalve.

FIG. 22b is a schematic of a torque key positioned at the bottom of abore hole for the purpose of preventing unintended rotation of thepump-turbine.

FIG. 23 is a pressure relief valve in accordance with the presentinvention.

FIGS. 24a and 24b is a pressure relief valve in accordance with thepresent invention shown closed and open respectively.

FIGS. 25a and 25b is a pressure relief valve in accordance with thepresent invention shown closed and open, respectively.

FIGS. 26a and 26b show a pressure relief valve in accordance with thepresent invention shown closed and open respectively.

FIGS. 27a and 27b show an installation of multiple pump-turbine/motorgenerators in a single bore hole.

FIG. 28 shows schematically one version of the pump turbine of thepresent invention.

FIG. 29 shows another version of the pump turbine of the presentinvention.

FIG. 30 shows another version of the pump turbine of the presentinvention incorporating a cylinder gate rather than wicket gates.

FIGS. 31-37 show various installation alternatives.

FIGS. 38-43 show various embodiments of a reversible pump turbine

FIGS. 44a-b show a flow inverter section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1a, 1b, and 1c , a conventional pumped storage plantwith a reversible pump-turbine is shown. There are several notablyexpensive features in such a conventional installation. These include;

-   -   1) A surge shaft that is typically needed to relieve waterhammer        that can result from a load rejection.    -   2) An underground powerhouse below tailwater level. Such a        powerhouse is expensive to construct and is at risk of flooding        due to human error or component failure. Flooding of an        underground powerhouse is a hazard to the facility itself as        well as to its operators.    -   3) The penstock and tailrace conduit must be routed, at great        expense to the same low elevation as the powerhouse itself.

Referring to FIG. 3a and FIG. 3 b, a reversible pump-turbineinstallation in accordance with the present invention is shown. Nounderground powerhouse is required. Instead, a vertical borehole orshaft 4 allows the pump-turbine and motor-generator assembly 1 to beinstalled, removed for maintenance as needed, and reinstalled, whileproviding the desired low height-of-setting of thee unit belowtailwater. The height of setting must be sufficiently low that the plantcavitation coefficient (plant sigma) is greater than the criticalcavitation coefficient (critical sigma), the cavitation coefficientbeing defined as the ratio of absolute pressure at the low-pressure sideof the runner divided by the vapor pressure of water at the temperatureof the water. Shaft 16 connects submersible motor-generator 8 topump-turbine stages 9, 10, 11, and 12. Vertical tailwater conduit 5connects to diffuser 14 above the point of entry of penstock 2. Pressurerelief valve 7 is preferably mounted to removable manifold 6. Removablemanifold 6 bolts down to foundation 13 and connects to tailrace conduit3 at flange 15 a. Tailrace conduit 3 leads to the lower reservoir notshown. It should be noted that the number of stages may be adjustedaccording to head, height of setting, speed, installation rating andother factors. Penstock 2 connects to upper reservoir 70. Tailraceconduit 3 connects to the lower reservoir 71. Water flows through outerannulus 17 of borehole 4 toward the upper reservoir 70 as a pump andtowards the pump turbine 43.

It should be noted that the removable portion may be further dividedinto conveniently separable subassemblies 6, 7, 14 and 5. For example,the manifold 6 might be lifted off first, the vertical portion of thetailrace conduit 5 might be lifted next, and the pump-turbine stages 9,10, 11, and 12 might be lifted last along with the motor-generator 8. Inthe case of a motor generator on top, the stator might be left in placewhile the rotor, shaft, and balance of the assembly might be lifted outlast.

Referring to FIGS. 4a and 4 b, a cross section of a pressure reliefvalve suitable of use in conjunction with the present invention is shownin its opened and closed positions respectively. Diffuser 14 isconnected to ribs 25. Ribs 25, ring 23, and ring 24 together radiallysupport bladder 18 on its inner diameter surface when its inflationpressure is greater than the pressure in shaft 17. Inflatable bladder 18is supported from below by flange 26 and on its OD by enclosure 7. Theair pressure in bladder 18 may be precisely adjusted to just stopleakage from shaft 17 into manifold 6 (at tailwater pressure).

Referring to FIGS. 5a and 5b a sectional elevation of a pump-turbine inaccordance with the present invention is shown. Runner 27 is designedaround a toroidal flow path wherein water reverses direction byapproximately 180 degrees in the meridional plane. Wicket gates 28 makeup an axial flow distributor. Turbine diffuser 29 recovers turbinerunner exit energy. Stay vanes 30 provide mechanical support to thedistributor hub 31, turbine diffuser 29 as well as wicket gate servosystem 32. Generator 33 is preferably located below the turbine.Hoisting piston 34 may be used to raise and lower, using water pressure,the entire pump-turbine assembly with connected draft tube segments,pressure relief valve and elbow. Hoisting piston 34 may incorporateupper seal ring 35 and lower seal ring 36 to maintain a seal whilepassing across the tailrace connection.

Hollow shaft 72 may be used as a heat pipe evaporator in conjunctionwith the runner 27 serving as a condenser. Electrical connector 73engages electrical receptacle assembly 74 when the machine is lowered.Shifting rings 75 and 76 provide torque to actuate wicket gates 28.

Borehole 4 is associated with rock face 77, grout 78 and steel liner 79.

Shaft seal assembly 80 keeps the generator enclosure dry.

Referring to FIG. 6, Piston assembly 34 supports generator 33 andpump-turbine 37 during raising and lowering. Valve 38 may be used toshut off water from penstock 39. Tailrace conduit 40 connects totailwater. Cover assembly 41 is removable.

Referring to FIG. 6, valve 42 may be used to fill vertical shaft 4during hydraulic raising and lowering of pump-turbine-motor-generatorassembly 43 with attached pipe, elbow, and pressure relief assemblies44, Lower portal 45 serves to launch TBM during construction phase andserves as pumping inlet works. Headworks 47 serves as upper portalduring construction and as service platform during maintenance. Crane 48may be used to disassemble draft tube segments, elbow assembly andpressure relief valve from pump-turbine for maintenance.

Referring to FIG. 7 an elbow assembly 49 is shown. Inflatable seal 50seals the upper end. Inflatable seal 51 closes the lower end. Elbow 52directs flow to the tailrace conduit. Spool 53 travels with thepump-turbine during maintenance moves.

Referring to FIG. 8 an installation is shown wherein the machine shaft54 is located under the headworks 55.

Referring to FIG. 9, the machine shaft 54 is located below the tailraceportal 56.

Referring to FIG. 10, machine shaft 54 is located at a location betweenthe headworks 55 and tailrace portal 56.

Referring to FIG. 11, Machine shaft 54 provides a connection topressurized reservoir 58 as well as to tailrace tunnel 59.

Referring to FIG. 12 a pressurized water reservoir 58 is shown inconjunction with a pressurized air column 59. Pump or pump/turbine 60may be in accordance with this invention or may be conventional. Air 59may be fed to a gas turbine generator set 61.

Referring to FIG. 13, spray cooling of the air being compressed may beused to provide isothermal air compression.

FIGS. 6, 7, 16, and 17 depict one of many possible constructionsequences.

Referring to FIG. 17, another embodiment is shown wherein inflatableseal 63 may also serve as a pressure relief valve.

Referring to FIG. 18, a combined seal and PRV 63 positioned in machineshaft 54 is shown in conjunction with elbow 52 and tailrace conduit 40.Machine shaft liner 64 is shown.

Referring to FIG. 17, another embodiment is shown wherein inflatableseal 63 may also serve as a pressure relief valve.

Referring to FIG. 18 another embodiment is shown with vanes 65 in elbow52.

Referring to FIGS. 19a and 19b a runner for a pump or reversible pumpturbine is shown wherein flow is directed along a smooth sinusoidal pathwithin the meridional plane. Blades (vanes) impart circumferentialacceleration vector and acceleration vectors within meridional plan toguide water through water passageway. Blade sequences may be normal tovector sum. The larger impellar is more efficient and provides higherhead per stage. Impellars may be best made by 3D printing.

Referring to FIGS. 21-23, various pressure relief valve configurationsare shown.

Referring to FIG. 24 splitter vanes are used.

Referring to FIG. 27, multiple pump turbines are shown sharing a commonpenstock 2 and tailrace conduit 3.

Referring to FIGS. 27A and 27 b, multiple submersible pump-turbines 62a-62 f, installed together in the same machine shaft 54 are shown.

FIGS. 28 through 30 show pump-turbines configured for installation on abulkhead in a common machine shaft.

Referring to FIG. 31, a medium/high voltage permanent-magnetmotor/generator 95 and battery storage array 98 are connected to autility grid 90 via a single cascade multilevel power converter. Thepower converter comprises a phase-shifting input transformer 92, powercells incorporating a regenerative-capable front-end 93, isolated DCbuses 95, and load-side inverters 94. Each power cell DC bus isconnected to a battery bank 98 via a disconnect switch 97. Theindividual DC bus 96 voltages are actively managed during operation tocharge or discharge the battery banks 98 independently of powerconsumption or generation by the motor/generator 95.

Referring to FIG. 32, a low-voltage permanent-magnet motor/generator 95and battery storage array 98 are connected to a utility grid 90 via asingle two-level power converter. The power converter comprises anactive front-end with line-side reactor 93, an intermediate DC bus 96,and a motor-side two-level inverter 94. The power converter is connectedto the grid through a disconnect 100 and step-up transformer 99. Thepower converter DC bus 96 is attached to a battery array 98 through adisconnect switch 97. The DC bus 96 voltage is actively managed duringoperation to charge or discharge the battery array 98 independently ofpower consumption or generation by the motor/generator 95.

Referring to FIG. 33, a permanent-magnet motor/generator 95 and batterystorage array 98 are connected to a utility grid 90 using parallel andindependent power converters. The converters may be connected usingindividual disconnects 91 incorporating protective functions. Themotor/generator 95 is connected using a regenerative AC/AC powerconverter 102. The battery array 98 is connected through DC busdisconnect(s) 97 to a grid-tie inverter 101. A step-up transformer 99increases inverter 101 output to grid voltage. Optionally, a disconnect100 is placed between transformer 99 and the battery inverter 101.

Referring to FIG. 34, a medium/high voltage doubly-fed induction machine103 and battery storage array 98 are connected to a utility grid 90. Therotor windings of the electric machine are connected to a cascademulti-level AC/AC drive with connected battery storage as described inFIG. 31. The stator windings of the electric machine are connected tothe grid through a disconnect 104.

Referring to FIG. 35, a medium/high voltage doubly-fed induction machine103 and battery storage array 98 are connected to a utility grid 90. Therotor windings of the electric machine are connected to a low-voltagetwo-level AC/AC drive with connected battery storage as described inFIG. 32. The stator windings of the electric machine are connected tothe grid through a disconnect 104.

Referring to FIG. 36, a medium/high voltage doubly-fed induction machine103 and battery storage array 98 are connected to a utility grid 90. Therotor windings of the electric machine are connected to regenerativeAC/AC drive 102. The stator windings of the electric machine areconnected to the grid through a disconnect 104. The battery storagearray is connected to a separate and independent DC/AC inverter 101 asdescribed in FIG. 33.

Referring to FIG. 37, multiple medium/high voltage permanent-magnetmotor/generators 95 are connected to a utility grid 90 in an arrangementthat allows either direct synchronous connection using direct on-linecontactors 105 in conjunction with forward/reverse selecting contactors106/107, which are interlocked to prevent simultaneous closure.Regenerative power converters 102 can be used to bring the electricmachines up to synchronous speed in either the pumping or generatingmode, or to operate at variable other-than-synchronous speeds.Phase-shift input transformers 92 connect the active front-end of theconverters 102 to the grid via disconnects 91. A matrix of disconnects108 allows any of the electric machines to be operated or started usingany of the power converters.

As can be easily understood from the foregoing, the basic concepts ofthe present invention may be embodied in a variety of ways. It involvesboth water control and actuator techniques as well as devices toaccomplish the appropriate water control or actuation. In thisapplication, the water control techniques are disclosed as part of theresults shown to be achieved by the various devices described and assteps which are inherent to utilization. They are simply the naturalresult of utilizing the devices as intended and described. In addition,while some devices are disclosed, it should be understood that these notonly accomplish certain methods but also can be varied in a number ofways. Importantly, as to all of the foregoing, all of these facetsshould be understood to be encompassed by this disclosure.

The discussion included in this application is intended to serve as abasic description. The reader should be aware that the specificdiscussion may not explicitly describe all embodiments possible; manyalternatives are implicit. It also may not fully explain the genericnature of the invention and may not explicitly show how each feature orelement can actually be representative of a broader function or of agreat variety of alternative or equivalent elements. Again, these areimplicitly included in this disclosure. Where the invention is describedin device-oriented terminology, each element of the device implicitlyperforms a function. Apparatus claims may not only be included for thedevice described, but also method or process claims may be included toaddress the functions the invention and each element performs. Neitherthe description nor the terminology is intended to limit the scope ofthe claims included in this patent application.

It should also be understood that a variety of changes may be madewithout departing from the essence of the invention. Such changes arealso implicitly included in the description. They still fall within thescope of this invention. A broad disclosure encompassing both theexplicit embodiment(s) shown, the great variety of implicit alternativeembodiments, and the broad methods or processes and the like areencompassed by this disclosure and may be relied upon for the claims forthis patent application. It should be understood that such languagechanges and broad claiming is accomplished in this filing. This patentapplication will seek examination of as broad a base of claims as deemedwithin the applicant's right and will be designed to yield a patentcovering numerous aspects of the invention both independently and as anoverall system.

Further, each of the various elements of the invention and claims mayalso be achieved in a variety of manners. This disclosure should beunderstood to encompass each such variation, be it a variation of anembodiment of any apparatus embodiment, a method or process embodiment,or even merely a variation of any element of these. Particularly, itshould be understood that as the disclosure relates to elements of theinvention, the words for each element may be expressed by equivalentapparatus terms or method terms—even if only the function or result isthe same. Such equivalent, broader, or even more generic terms should beconsidered to be encompassed in the description of each element oraction. Such terms can be substituted where desired to make explicit theimplicitly broad coverage to which this invention is entitled. As butone example, it should be understood that all actions may be expressedas a means for taking that action or as an element which causes thataction. Similarly, each physical element disclosed should be understoodto encompass a disclosure of the action which that physical elementfacilitates. Regarding this last aspect, as but one example, thedisclosure of a “means for actuating” or an “actuator” should beunderstood to encompass disclosure of the act of “actuating”—whetherexplicitly discussed or not—and, conversely, were there effectivelydisclosure of the act of “actuating”, such a disclosure should beunderstood to encompass disclosure of an “actuator” and even a “meansfor actuating”. Such changes and alternative terms are to be understoodto be explicitly included in the description.

Any acts of law, statutes, regulations, or rules mentioned in thisapplication for patent; or patents, publications, or other referencesmentioned in this application for patent are hereby incorporated byreference. In addition, as to each term used it should be understoodthat unless its utilization in this application is inconsistent withsuch interpretation, common dictionary definitions should be understoodas incorporated for each term and all definitions, alternative terms,and synonyms such as contained in the Random House Webster's UnabridgedDictionary, second edition are hereby incorporated by reference.Finally, all references listed in the list of References To BeIncorporated By Reference In Accordance With The Patent Application orother information statement filed with the application are herebyappended and hereby incorporated by reference, however, as to each ofthe above, to the extent that such information or statementsincorporated by reference might be considered inconsistent with thepatenting of this/these invention(s) such statements are expressly notto be considered as made by the applicant(s).

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1. A pumped storage system comprising: an upper water storage basin, alower water storage basin, a reversible pump-turbine connected to saidupper water storage basin by a penstock conduit and also connected tosaid lower water storage basin by means of a tail water conduit, amotor-generator operably connected to said pump-turbine; wherein saidpump-turbine comprises multiple stages, and wherein said pump turbine ispositioned in a vertical shaft at an elevation below the surface of saidlower water storage basin, and wherein said pump-turbine is axiallyremovable from said vertical shaft.
 2. (canceled)
 3. A pumped storagesystem as described in claim 1, wherein said penstock conduit and saidtail water conduit are coaxially positioned in said vertical shaft abovesaid pump-turbine.
 4. (canceled)
 5. A pumped storage system as describedin claim 1, wherein said motor-generator is positioned below saidpump-turbine.
 6. (canceled)
 7. A pumped storage system as described inclaim 3, wherein said coaxial conduits comprise an inner conduit and anouter conduit, and further comprising a removable manifold for directingwater in said inner conduit to said lower water storage basin and fordirecting water from said upper water storage basin to said penstockconduit.
 8. A pumped storage system as described in claim 7, whereinsaid manifold further comprises a pneumatically controlled pressurerelief valve for reducing surge pressure in said penstock conduit.
 9. Apumped storage system as described in claim 1, further comprising ahoisting piston positioned below said pump-turbine for selectivelyraising and lowering said pump-turbine in said vertical shaft.
 10. Apumped storage system having an upper water storage basin, a lower waterstorage basin, and a reversible pump-turbine connected to said upperwater storage basin by a penstock conduit and also connected to saidlower water storage basin by means of a tail water conduit, wherein saidpump-turbine is positioned in a vertical shaft at an elevation below thesurface of said lower water storage basin; wherein said pump-turbine isaxially removable from said vertical shaft; wherein said conduits arecoaxially positioned in said vertical shaft.
 11. A reversiblepump-turbine comprising: a submersible motor-generator. wherein saidmotor-generator is located beneath one or more pump-turbine stages, andwherein said reversible pump-turbine is located in a vertical shaft fromwhich it is removable. 12-13. (canceled)
 14. A reversible pump-turbineas described in claim 11 further comprising a removable manifold fixedto the top of the shaft during operation.
 15. A reversible pump-turbineas described in claim 14 wherein the removable manifold includes apressure relief valve for relieving excess head pressure to thetailwater conduit.
 16. A reversible pump-turbine as described in claim15 wherein the pressure relief valve is comprised of an elastomericdiaphragm held by controlled gas pressure against one or more orificescontaining headwater pressure.
 17. A reversible pump-turbine asdescribed in claim 11 wherein the motor-generator is located above theturnout connecting the headwater to the vertical shaft.
 18. A reversiblepump-turbine as described in claim 11 wherein the pump-turbine iscomprised of multiple stages.